Attitude control of an underactuated satellite in presence of disturbance torque with optimal motion planning

Abstract

The failure of mechanical components is a common phenomenon in satellites. This failure can happen in the satellite attitude control system, which causes that the control system of the satellite becomes underactuated. There have been many attempts to control the orientation of underactuated satellites. However, in most studies, the inertia matrix of the satellite is assumed to be diagonal with respect to the body coordinate system, and no limitations on the amount of torque applied by the reaction wheels have been considered. In this paper, at first, it is attempted to control the satellite using the motion planning method. The satellite control inputs are assumed to be cubic spline with some unknown parameters. The spline parameters are determined by minimizing a cost function defined such that the attitude of the satellite tracks desired preset values. Also, in the simulations, the inertia matrix of the satellite is considered non-diagonal and the maximum torques applied by the reaction wheels are considered limited. Then, the effect of disturbance on the controlled satellite is considered which is modeled by some external torques, and the proposed method is modified by repeating the control algorithm in short time horizons. Finally, the method is customized to be used in tracking an object by the satellite in the space which is applicable in time varying maneuvers such as observation and communications. The performance of the proposed method is demonstrated via numerical simulations.